"Simplicity does not precede complexity, but follows it." -- Alan Perlis
"Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
"The only real mistake is the one from which we learn nothing." -- John Powell

"Simplicity does not precede complexity, but follows it." -- Alan Perlis
"Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
"The only real mistake is the one from which we learn nothing." -- John Powell

It is of course, random. The fact still remains that from a mathematical standpoint, the chance of a hit becomes greater than 0.5 when there are 23 or more people. This doesn't mean the hit will happen, but it becomes more and more likely.

In other words, given an infinite set of sets of 23 people, approximately half of such sets (only approximate, because the actual halfway point is not an integral number of people, but a non-integral number of people is impossible) will contain at least one coincident birthday. But you shouldn't be that surprised if any GIVEN set does not contain a hit, any more than you should be surprised by flipping 8 heads in 10 flips.

Now, if you had a set of 367 people and got no hits, you should be VERY surprised, since there are only 366 days in the year (worst case, counting leap years)